JP5036215B2 - Piezoelectric thin film resonator and method for adjusting resonance frequency of piezoelectric thin film resonator - Google Patents

Description

  The present invention relates to a piezoelectric thin film resonator capable of adjusting a resonance frequency and a method for adjusting a resonance frequency of the piezoelectric thin film resonator.

  Conventionally, the resonance frequency of a piezoelectric thin film resonator is adjusted by lowering the resonance frequency of the piezoelectric thin film resonator by forming a metal mass-added film on the drive electrode that constitutes the piezoelectric thin film resonator. This has been performed by removing the drive electrode constituting the thin film resonator by dry etching to increase the resonance frequency of the piezoelectric thin film resonator (for example, Patent Document 1).

JP 2002-359534 A

  However, in the conventional technology, it is necessary to adjust the resonance frequency of the piezoelectric thin film resonator in a vacuum, so that a complicated device equipped with a vacuum chamber is indispensable, and the manufacturing cost and manufacturing time of the piezoelectric thin film resonator are required. There were many problems.

  On the other hand, as a method for adjusting the resonance frequency of the piezoelectric thin film resonator in the atmosphere, a method of removing a metal mass-added film formed on the drive electrode constituting the piezoelectric thin film resonator with a laser beam is also conceivable. . However, in this method, the mass-added film is removed by melting and evaporation throughout the film thickness direction, so that the planar pattern of the mass-added film changes and spurious is generated in the piezoelectric thin film resonator. is there.

  The present invention has been made to solve this problem, and aims to adjust the resonance frequency of the piezoelectric thin film resonator in the atmosphere and to suppress the occurrence of spurious due to the adjustment of the resonance frequency of the piezoelectric thin film resonator. And

In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a mass-added film for adding mass is formed on a piezoelectric thin film resonator, and a resonance step of the piezoelectric thin film resonator is reduced below a target frequency; The mass-added film is ablated by irradiating the film, and the entire mass-added film is uniformly thinned without affecting the planar pattern of the mass-added film. And adjusting the resonance frequency of the piezoelectric thin film resonator with an irradiation step of raising the frequency to a target frequency. In the piezoelectric thin film resonator, electrode pairs face each other with a piezoelectric thin film interposed therebetween. In the forming step, the mass-added film is formed in the entire facing region where the electrode pairs face each other with the piezoelectric thin film interposed therebetween. In the forming step, the mass addition film is formed only in the facing region.

  According to a second aspect of the present invention, the forming step includes a film forming step of forming a photosensitive resin, and a patterning step of patterning the photosensitive resin by photolithography to obtain the mass addition film. It is the adjustment method of the resonant frequency of the described piezoelectric thin film resonator.

  According to a third aspect of the present invention, in the irradiation step, the electromagnetic wave is irradiated while measuring the resonance frequency of the piezoelectric thin film resonator, and the electromagnetic wave is irradiated in synchronization with the resonance frequency of the piezoelectric thin film resonator rising to the target frequency. The method for adjusting the resonance frequency of the piezoelectric thin film resonator according to claim 1 or 2 to be stopped.

  The invention of claim 4 further includes a determination step of determining an irradiation condition of the electromagnetic wave in accordance with a deviation between a resonance frequency of the piezoelectric thin film resonator and a target frequency prior to the irradiation step. This is a method for adjusting the resonance frequency of the piezoelectric thin film resonator.

  According to a fifth aspect of the present invention, in the forming step, the mass addition film is formed on each piezoelectric thin film resonator included in the piezoelectric thin film resonator assembly, and in the irradiation step, the piezoelectric thin film resonance in the aggregate is formed. The method for adjusting the resonance frequency of the piezoelectric thin film resonator according to claim 1 or 2, wherein the assembly is irradiated with an electromagnetic wave having a distribution of irradiation conditions corresponding to a distribution of the resonance frequency of the child.

  According to a sixth aspect of the present invention, in the forming step, the mass-added film is formed on each piezoelectric thin film resonator included in the piezoelectric thin film resonator assembly, and in the irradiation step, the piezoelectric thin film resonance in the aggregate is formed. 3. The method of adjusting a resonance frequency of a piezoelectric thin film resonator according to claim 1, wherein the aggregate is irradiated with an electromagnetic wave having a uniform irradiation condition according to a deviation between a representative value of the resonance frequency of the child and a target frequency. is there.

According to a seventh aspect of the present invention, there is provided a piezoelectric thin film, an electrode pair opposed to each other with the piezoelectric thin film interposed therebetween, and a laminated structure including the piezoelectric thin film and the electrode pair. A piezoelectric thin-film resonator includes a mass-added film whose mass is adjusted by ablation processing according to a deviation from a target frequency. The mass addition film is formed over the entire facing region where the electrode pair faces each other with the piezoelectric thin film interposed therebetween. The mass addition film is formed only in the facing region. The mass addition film is thinned uniformly throughout the mass addition film without affecting the planar pattern of the mass addition film.

  According to the first to seventh aspects of the invention, the resonance frequency of the piezoelectric thin film resonator can be adjusted in the atmosphere. According to the first to seventh aspects of the invention, since the planar pattern of the mass-added film does not change, the occurrence of spurious due to the adjustment of the resonance frequency of the piezoelectric thin film resonator can be suppressed.

  According to invention of Claim 2, a mass addition film | membrane can be formed correctly only on a desired area | region.

<1 First Embodiment>
<1.1 Wafer>
FIG. 1 is a cross-sectional view schematically showing a wafer W to which a method for adjusting a resonance frequency of a piezoelectric thin film resonator according to a preferred embodiment of the present invention (hereinafter, “frequency adjustment method”) is applied. Hereinafter, a frequency adjustment method according to a preferred embodiment of the present invention will be described with reference to FIG. 1. However, in the following description, the application target of the frequency adjustment method according to the present invention is limited to the wafer W shown in FIG. Does not mean that. Therefore, the frequency adjusting method according to the present invention can also be applied to a known piezoelectric thin film resonator or the like in which the lower surface electrode, the piezoelectric thin film, and the upper surface electrode are sequentially epitaxially grown on the support substrate. The frequency adjusting method according to the present invention can also be applied to a filter, a duplexer, a triplexer, a trap, and the like that combine a plurality of piezoelectric thin film resonators.

As shown in FIG. 1, a wafer W includes an aggregate of piezoelectric thin film resonators 1 in which a large number (typically several hundred to several thousand) of piezoelectric thin film resonators 1 are regularly arranged on the upper surface. As shown in the cross-sectional view of FIG. 2, after the adjustment of the resonance frequency F _r of all the piezoelectric thin film resonators 1 is completed, the piezoelectric thin film resonators 1 are expected to be separated. .

  The wafer W has a structure in which an adhesive layer 12, a cavity forming film 13, a lower surface electrode 15, a piezoelectric thin film 16, and an upper surface electrode 17 (171 to 172) are laminated on the support substrate 11 in this order.

  The piezoelectric thin film 16 is obtained by removing the piezoelectric substrate. More specifically, the piezoelectric thin film 16 removes a piezoelectric substrate having a thickness that can withstand its own weight (for example, 50 μm or more) to a thickness (for example, 10 μm or less) that cannot withstand its own weight. It can be obtained by thinning.

As the piezoelectric material constituting the piezoelectric thin film 16, a piezoelectric material having desired piezoelectric characteristics can be selected, but quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), Select single crystal materials that do not contain grain boundaries such as lithium tetraborate (Li ₂ B ₄ O ₇ ), zinc oxide (ZnO), potassium niobate (KNbO ₃ ) and langasite (La ₃ Ga ₃ SiO ₁₄ ) It is desirable.

  In addition, as the crystal orientation in the piezoelectric thin film 16, a crystal orientation having desired piezoelectric characteristics can be selected. Here, the crystal orientation in the piezoelectric thin film 16 is preferably a crystal orientation in which the temperature characteristics of the resonance frequency and antiresonance frequency of the piezoelectric thin film resonator 1 are favorable, and the crystal orientation in which the frequency temperature coefficient is “0”. Is more desirable.

  The removal processing of the piezoelectric substrate is performed by mechanical processing such as cutting, grinding and polishing, and chemical processing such as etching. Here, if a plurality of removal processing methods are combined and the piezoelectric substrate is removed while switching the removal processing method step by step from the removal processing method with a high processing speed to the removal processing method with a small process alteration occurring on the processing target. The quality of the piezoelectric thin film 16 can be improved and the characteristics of the piezoelectric thin film resonator 1 can be improved while maintaining high productivity. For example, after performing grinding in which a piezoelectric substrate is brought into contact with fixed abrasive grains and polishing in which a piezoelectric substrate is brought into contact with loose abrasive grains in order, a work-affected layer generated on the piezoelectric substrate by the polishing is finished and polished. If it removes by this, the speed at which the piezoelectric substrate is cut can be increased, the productivity of the piezoelectric thin film resonator 1 can be improved, and the quality of the piezoelectric thin film 16 can be improved. 1 characteristic can be improved.

  In the piezoelectric thin film 16, a via hole VH1 penetrating the upper surface and the lower surface is formed.

  The upper surface electrode 17 and the lower surface electrode 15 are conductor thin films formed by depositing a conductive material on the upper surface and the lower surface of the piezoelectric thin film 16, respectively.

  The conductive material constituting the upper surface electrode 17 and the lower surface electrode 15 is not particularly limited, but aluminum (Al), silver (Ag), copper (Cu), platinum (Pt), gold (Au), chromium (Cr), nickel It is desirable to select from metals such as (Ni), molybdenum (Mo), tungsten (W) and tantalum (Ta). Of course, an alloy may be used as the conductive material constituting the upper electrode 17 and the lower electrode 15. Further, the upper surface electrode 17 and the lower surface electrode 15 may be formed by stacking a plurality of types of conductive materials.

  The upper surface electrode 171 faces the lower surface electrode 15 with the piezoelectric thin film 16 in between in the facing region E1 of the piezoelectric thin film resonator 1. The upper surface electrode 171 is drawn out from the facing area E1 in a predetermined direction, and the tip thereof is a pad P11 to which wiring to the outside is connected.

  The lower surface electrode 15 is drawn out in the direction opposite to the upper surface electrode 17 from the facing region E1.

  The upper surface electrode 172 is opposed to the lower surface electrode 15 with the piezoelectric thin film 16 in between, except for the opposed region E1. The upper surface electrode 172 and the lower surface electrode 15 are electrically short-circuited by a via hole VH1 formed in the piezoelectric thin film 16, and the upper surface electrode 172 is a pad P12 to which wiring to the outside is connected.

  With such a pattern of the upper surface electrode 17 and the lower surface electrode 15, in the piezoelectric thin film resonator 1, when an excitation signal is applied to the pads P11 and P12, thickness longitudinal vibration (or thickness shear vibration) is excited in the opposing region E1. Is done.

The cavity forming film 13 is an insulator film obtained by forming an insulating material. The insulating material constituting the cavity forming film 13 is not particularly limited, but is preferably selected from insulating materials such as silicon dioxide (SiO ₂ ).

  The cavity forming film 13 is formed in a region other than the facing region E1 of the piezoelectric thin film 16, and forms a cavity C1 that separates the piezoelectric thin film 16 in the facing region E1 from the support substrate 11.

  The support substrate 11 supports the piezoelectric substrate on which the lower surface electrode 15 and the cavity forming film 13 are formed on the lower surface via the adhesive layer 12 when the piezoelectric substrate is removed during the manufacturing of the piezoelectric thin film resonator 1. It has a role as a support. In addition, after the piezoelectric thin film resonator 1 is manufactured, the support substrate 11 has the piezoelectric thin film 16 having the lower surface electrode 15 and the cavity forming film 13 formed on the lower surface and the upper surface electrode 17 formed on the upper surface via the adhesive layer 12. It also has a role as a support body that supports. Accordingly, the support substrate 11 is required to be able to withstand the force applied when the piezoelectric substrate is removed, and not to decrease in strength even after the piezoelectric thin film resonator 1 is manufactured.

  The material and thickness of the support substrate 11 can be appropriately selected so as to satisfy such requirements. However, the material of the support substrate 11 is a material having a thermal expansion coefficient close to that of the piezoelectric material constituting the piezoelectric thin film 16, more preferably a material having the same thermal expansion coefficient as the piezoelectric material constituting the piezoelectric thin film 16, for example, a piezoelectric body If the same material as the piezoelectric material constituting the thin film 16 is used, warping and breakage due to the difference in thermal expansion coefficient can be suppressed during the manufacturing of the piezoelectric thin film resonator 1. Thus, characteristic fluctuations and breakage due to the difference in thermal expansion coefficient can be suppressed. When a material having an anisotropic thermal expansion coefficient is used, it is desirable to consider that the piezoelectric thin film 16 and the support substrate 11 have the same thermal expansion coefficient in each direction. When the same piezoelectric material is used for the body thin film 16, it is desirable that the crystal orientations of the support substrate 11 and the piezoelectric thin film 16 are matched.

  The adhesive layer 12 serves to bond and fix the piezoelectric substrate having the lower surface electrode 15 and the cavity forming film 13 formed on the lower surface to the support substrate 11 when the piezoelectric substrate is removed during the manufacturing process of the piezoelectric thin film resonator 1. have. In addition, after the piezoelectric thin film resonator 1 is manufactured, the adhesive layer 12 adheres the piezoelectric thin film 16 having the lower electrode 15 and the cavity forming film 13 formed on the lower surface and the upper electrode 17 formed on the upper surface to the support substrate 11. It also has a fixing role. Therefore, the adhesive layer 12 is required to be able to withstand the force applied when the piezoelectric substrate is removed and that the adhesive force does not decrease even after the piezoelectric thin film resonator 1 is manufactured.

  Desirable examples of the adhesive layer 12 satisfying such requirements include an organic adhesive, preferably an epoxy adhesive having a filling effect and exhibiting sufficient adhesive force even if the object to be bonded is not completely flat ( Examples thereof include an adhesive layer 12 formed of an epoxy resin adhesive using thermosetting) and an acrylic adhesive (an acrylic resin adhesive using both photo-curing property and thermosetting property). By adopting such a resin, it is possible to prevent an unexpected gap from being generated between the piezoelectric substrate and the support substrate 11 and to prevent a crack or the like from being generated during the removal processing of the piezoelectric substrate by the gap. It is. However, this does not prevent the piezoelectric thin film 16 and the support substrate 11 from being bonded and fixed by the other adhesive layer 12.

<1.2 Adjustment of Resonant Frequency of Piezoelectric Thin Film Resonator>
FIG. 3 is a flowchart illustrating the frequency adjustment method according to the first embodiment of the present invention. 4 to 6 are cross-sectional views schematically showing the wafer W in the course of frequency adjustment. In the first embodiment, the resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W individually adjusted, variations of the resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W (hereinafter, "the wafer Variation ”). Here, the target frequency F _T a particular frequency (e.g., 2 GHz) need not be, the particular frequency range allowed a certain deviation to a particular frequency (e.g., 2 GHz ± 1 MHz) may be.

○ Wafer preparation;
Referring to FIG. 3, in the frequency adjustment method according to the first embodiment, first, target film thicknesses of the piezoelectric thin film 16, the upper surface electrode 17, and the lower surface electrode 15 are set in consideration of variations in the wafer before frequency adjustment. it allows almost all of the resonant frequency F _R of the piezoelectric thin film resonator 1 prepares a wafer above the target frequency F _T (step S101). Here, “substantially all” means that the resonance frequency F _{R of} all the piezoelectric thin film resonators 1 included in the wafer W is preferably higher than the target frequency F _T , but the resonance frequency F _R is other piezoelectric thin film resonance. it is a effect that the resonant frequency F _R of the child 1 and the significantly different part abnormal piezoelectric thin film resonator 1 may allow below the target frequency F _T.

○ Resist film formation;
Subsequently, as shown in FIG. 4, a resist liquid film layer 18 is uniformly formed on the entire upper surface of the wafer W (step S102). The film thickness of the resist liquid film layer 18 at the time of performing the solidification of the resist film 19 (step S105 described later), the resonance frequency of the piezoelectric thin film resonator 1 of substantially all contained in the wafer W F _R is the target frequency F _T The thickness may be set to be less than 0.5 μm, typically about 0.5 μm. The resist liquid film layer 18 can be formed by a spin coater or a slit coater. When the resist liquid film layer 18 is formed by a spin coater, for example, the stock solution is diluted with a solvent such as cyclopentanone and adjusted to an appropriate viscosity. What is necessary is just to dripped the photoresist liquid which it did to the wafer W which rotates at about 4000 RPM.

  Next, the solvent contained in the resist liquid film layer 18 is evaporated to obtain a resist film having no fluidity (step S103). The evaporation of the solvent can be performed, for example, by placing the wafer W on a hot plate and heating it at 90 ° C. for 20 minutes.

Further, as shown in FIG. 5, the formed resist film 19 is patterned by photolithography to obtain a wafer W in which the resist film 19 remains only on the facing region E1 (step S104). For example, the resist film 19 is irradiated with light of 8 mW / cm ² for 30 seconds using an aligner to transfer the photomask pattern to the resist film 19 for 30 seconds. Patterning can be performed by developing the resist film 19 by immersion for 10 minutes.

  Subsequently, the wafer W is cleaned and the resist film 19 is solidified (step S105). For example, the wafer W may be cleaned by immersing the wafer W in a solvent that does not attack resist such as isopropyl alcohol for 5 minutes and then drying the wafer W with a spin dryer. The resist film 19 may be solidified by, for example, heating the wafer W at 200 ° C. for 3 hours using an oven.

In step S102 to S105, on opposite region E1 of the piezoelectric thin film resonator 1 contained in the wafer W is formed resist film 19 at which the mass adding film of adding mass, initially not exceed the target frequency F _T The resonance frequency F _R of the piezoelectric thin film resonator 1 is lowered to the target frequency F _T or less.

  In the above description, the example in which the resist film 19 is used as the mass addition film has been described. However, another photosensitive resin film that can be ablated, for example, a photosensitive polyimide film may be used as the mass addition film.

  In the above description, the resist film 19 is patterned by photolithography so that the resist film 19 remains accurately only on the facing region E1 and the pads P11 and P12 are exposed. If the resist liquid film layer 18 is not formed, the patterning of the resist film 19 is not necessarily required.

○ Frequency adjustment;
Then the prober wired to pad P11 and P12 of one film bulk acoustic resonator 1A to be adjusted resonant frequency F _R, so that it can measure the resonant frequency F _R of the piezoelectric thin film resonator 1A using a network analyzer To. Then, as shown in FIG. 6, while measuring the resonant frequency F _R of the piezoelectric thin film resonator 1A, the resist film 19 formed on opposite region E1 of the piezoelectric thin-film resonator 1A electromagnetic waves (ultraviolet UV) radiation Thus, the resist film 19 is ablated (step S106).

At this time, since the mass of the resist film 19 as ablation of the resist film 19 is advanced decreases, although ablation of the resist film 19 is the resonant frequency F _R of the piezoelectric thin film resonator 1A with the progress increases, the piezoelectric thin film resonant frequency F _R of the resonator 1A is synchronized to rise to the target frequency F _T if discontinued irradiation ( "YES" in step S107) electromagnetic waves (step S108), the resonance frequency F of the piezoelectric thin film resonator 1A You can adjust the _R to precisely target frequency F _T. Of course, up to the resonant frequency F _R of the piezoelectric thin film resonator 1A is raised up to the target frequency F _T is ( "NO" in step S107), the measurement and the piezoelectric thin film resonator 1A resonant frequency F _R of the piezoelectric thin film resonator 1A What is necessary is just to continue irradiation of the electromagnetic wave to the resist film 19 formed on the opposing area | region E1 as it is. Incidentally, if the electromagnetic wave irradiation time of the resonant frequency F _R of the piezoelectric thin film resonator 1A also exceeds the predetermined time has not increased to the target frequency F _T is regarded as the piezoelectric thin film resonator 1A is poor, the piezoelectric the adjustment of the resonance frequency F _R of the thin film resonator 1A may be abandoned.

The electromagnetic source used in the ablation processing by irradiating an electromagnetic wave only the resist film 19 formed on the selectively opposite region E1 of the piezoelectric thin film resonator 1A to be adjusted resonant frequency F _R, adjacent piezoelectric It is desirable to use a light source with a small divergence that does not irradiate electromagnetic waves to the resist film 19 formed on the opposing region E1 of the thin film resonator 1B, and an ultraviolet laser such as an excimer laser or a YAG fourth harmonic laser is used. It is particularly desirable to adopt it. However, this does not prevent the adoption of an ultraviolet lamp as a light source of ultraviolet UV used for ablation processing. In the case where an ultraviolet lamp is used as the electromagnetic wave light source, it is sufficient to contrive to collect the electromagnetic wave with a lens or limit the irradiation area of the electromagnetic wave with a metal mask.

  In addition, as a light source of a wavelength other than ultraviolet light, a high power density is obtained by using a YAG laser which is a near infrared wavelength light source or a YAG second harmonic laser which is a visible light wavelength light source, by using a short pulse and a highly condensed beam. As a result, pseudo ablation processing can be performed, or ablation processing by multiphoton absorption can be performed. By using these light sources depending on the absorption characteristics of the workpiece, processing with high processing efficiency can be performed.

  Also, ablation processing can be performed by using a light source having a wavelength called extreme ultraviolet rays having a wavelength of several tens of nm, such as a laser plasma EUV lithography light source. Processing with high patterning accuracy can be performed.

In such an ablation process, if an electromagnetic wave having an appropriate amount of light is irradiated, a polymer bond chain on the surface of the resist film 19 can be cut and the resist film 19 can be sequentially removed from the surface. The entire film 19 can be thinned uniformly, and the planar pattern of the resist film 19 is not affected. For this reason, in the frequency adjustment method according to the first embodiment, it is possible to suppress the occurrence of spurious due to the frequency adjustment. Moreover, such ablation, because it can be performed in the atmosphere, the frequency adjustment method according to the first embodiment, the resonant frequency F _R of the piezoelectric thin film resonator 1 can be adjusted in the atmosphere.

In the frequency adjustment method according to the first embodiment, until the piezoelectric thin film resonator 1 all contained in the wafer W to adjust the resonant frequency F _R is completed (in step S109 "NO"), one of the piezoelectric thin film About resonator 1 is adjustment of the resonance frequency F _R to end, by moving the wafer W on the stage, or, by scanning the light source, by moving the irradiation range of the electromagnetic waves (step S110), the resonance frequency F _R There adjusted similarly resonant frequency F _R for the other piezoelectric thin film resonator 1 that has not been adjusted yet.

Target frequency F _T is to sometimes the piezoelectric thin-film resonator of all included in the wafer W is set to the same value, in some cases set to a different value depending on the purpose.

<2 Second Embodiment>
FIG. 7 is a flowchart illustrating a frequency adjustment method according to the second embodiment of the present invention. In the second embodiment, like the first embodiment, the resist film 19 a resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W is adjusted individually by ablation processing by the electromagnetic wave, the wafer in the dispersion Suppressed.

  Referring to FIG. 7, in the frequency adjustment method according to the second embodiment, first, wafer preparation (step S201) and resist film formation (steps S202 to S205) are performed in the same procedure as in the first embodiment.

Followed in frequency adjustment, first, by sequentially connecting the prober to pad P11 and P12 of the piezoelectric thin film resonator 1 contained in the wafer W, sequentially measures the resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W (Step S206).

Next, with reference to the previously experimentally investigated in advance electromagnetic wave irradiation conditions (light intensity or irradiation time) and the relationship between the rise of the resonance frequency F _R of the piezoelectric thin film resonator 1, all of the piezoelectric contained in the wafer W the thin film resonator 1, in accordance with the deviation between the resonance frequency F _R and the target frequency F _T, to determine the irradiation conditions of the electromagnetic waves (step S207). In step S207, for example, if the rising speed D of the resonance frequency F _R of the piezoelectric thin film resonator 1 when the resist film 19 is irradiated with electromagnetic waves is experimentally examined in advance, the piezoelectric thin film resonance of the resonance frequency F _R is obtained. The irradiation time of the electromagnetic wave for the child 1 can be determined as (F _T −F _R ) / D.

Subsequently, according to the determined irradiation condition, the resist film 19 is ablated by irradiating the resist film 19 formed on the opposing region E1 of one piezoelectric thin film resonator 1 with the electromagnetic wave, and the resonance frequency F _R Is adjusted (step S208).

  The irradiation conditions for the specific piezoelectric thin film resonator 1 may be determined prior to irradiating the resist film 19 on the excitation region E1 of the specific piezoelectric thin film resonator 1 with the electromagnetic wave. Thus, it is not essential to simultaneously determine the irradiation conditions for all the piezoelectric thin film resonators 1 included in the wafer W. Therefore, it is allowed to determine the irradiation conditions for the other piezoelectric thin film resonators 1 to be irradiated with the electromagnetic waves next while the one piezoelectric thin film resonator 1 is irradiated with the electromagnetic waves.

Then, the frequency adjustment method according to the second embodiment, until the piezoelectric thin film resonator 1 all contained in the wafer W to adjust the resonant frequency F _R is completed (in step S209 "NO"), one of the piezoelectric thin film When the adjustment of the resonance frequency F _R for the resonator 1 is completed, the irradiation range of the electromagnetic wave is moved by moving the wafer W on the stage or by scanning the light source (step S210), and the resonance frequency F _R. There adjusted similarly resonant frequency F _R for the other piezoelectric thin film resonator 1 that has not been adjusted yet.

Target frequency F _T is to sometimes the piezoelectric thin-film resonator of all included in the wafer W is set to the same value, in some cases set to a different value depending on the purpose.

Even in the frequency adjustment method according to the second embodiment, it is possible to suppress the occurrence of spurious due to the frequency adjustment and to reduce the resonance frequency F _R of the piezoelectric thin film resonator 1 as in the frequency adjustment method according to the first embodiment. Can be adjusted in the atmosphere.

<3 Third Embodiment>
FIG. 8 is a flowchart illustrating a frequency adjustment method according to the third embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing the wafer W in the course of frequency adjustment. In the third embodiment, like the first embodiment, by ablation of the resist film 19 in the electromagnetic wave, and adjust the resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W, suppress wafer in variation Although it is to point to adjust the resonance frequency F _R of the whole of the piezoelectric thin film resonator 1 contained in the wafer W collectively is different from the first embodiment.

  Referring to FIG. 8, in the frequency adjustment method according to the third embodiment, first, wafer preparation (step S301) and resist film formation (steps S302 to S305) are performed in the same procedure as in the first embodiment.

Subsequently, irradiation with electromagnetic waves given the distribution of irradiation conditions according to the distribution of the resonant frequency F _R of the piezoelectric thin film resonator 1 of the wafer W to the wafer W (step S306). In step S306, for example, the film thickness of the piezoelectric thin film 16 (or the upper surface electrode 17 or the lower surface electrode 15) decreases as it approaches the outer periphery of the wafer W, so that the piezoelectric thin film resonator 1 approaches the outer periphery of the wafer W. If the resonant frequency F _R that is high in, as shown in FIG. 9, irradiates the electromagnetic wave amount decreases toward the periphery of the wafer W to the entire upper surface of the wafer W. Alternatively, the entire upper surface of the wafer W can be irradiated with an electromagnetic wave whose irradiation time becomes shorter as it approaches the outer periphery of the wafer W. Of course, as in the second embodiment, actually measured resonance frequency F _R of the whole of the piezoelectric thin film resonator 1 contained in the wafer W, specific distribution wafers W of the resonance frequency F _R of the piezoelectric thin film resonator 1 You may make it specify for every.

Even in the frequency adjustment method according to the third embodiment, it is possible to suppress the occurrence of spurious due to the frequency adjustment as well as the resonance frequency F _R of the piezoelectric thin film resonator 1 as in the frequency adjustment method according to the first embodiment. Can be adjusted in the atmosphere. The frequency adjusting method according to the third embodiment is particularly effective for suppressing variations in the wafer whose tendency is known in advance.

<4 Fourth Embodiment>
FIG. 10 is a flowchart illustrating a frequency adjustment method according to the fourth embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing the wafer W in the course of frequency adjustment. Also in the fourth embodiment, like the first embodiment, by ablation of the resist film 19 in the electromagnetic wave, although adjusting the resonance frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W, the wafer W The resonance frequencies F _R of all the piezoelectric thin film resonators 1 included in the wafer are collectively adjusted, whereby variations in the resonance frequencies F _R of the piezoelectric thin film resonators 1 between a plurality of wafers W (hereinafter referred to as “wafer variations between wafers”). ") Is different from the first embodiment.

  Referring to FIG. 10, in the frequency adjustment method according to the fourth embodiment, first, wafer preparation (step S401) and resist film formation (steps S402 to S405) are performed in the same procedure as in the first embodiment.

Subsequently, the pad P11 and P12 of the piezoelectric thin film resonator 1 contained in the wafer W by sequentially connecting the prober sequentially measuring the resonant frequency F _R of the piezoelectric thin film resonator 1 contained in the wafer W (step S406).

Next, with reference to the previously experimentally investigated in advance electromagnetic wave irradiation conditions (light intensity or irradiation time) and the relationship between the rise of the resonance frequency F _R of the piezoelectric thin film resonator 1, the piezoelectric thin film resonator 1 of the wafer W representative value of the resonant frequency F _R of (e.g., average value or statistics mode value, etc.) to determine the irradiation conditions in accordance with the deviation between the target frequency F _T (step S407). In step S407, for example, if the rising speed D of the resonant frequency F _R of the case of applying an electromagnetic wave in the resist film 19 are investigated experimentally in advance, electromagnetic irradiation time for the wafer W is (F _T -F _RA ) / D. However, “F _RA ” is an average value of the resonance frequencies F _R of all the piezoelectric thin film resonators 1 included in the wafer W.

Then, according to the determined irradiation conditions, by the amount of light and the irradiation time as shown in FIG. 11 is irradiated with uniform electromagnetic waves over the entire surface of the upper surface of the wafer W, the resist film 19 and ablation, adjusting the resonance frequency F _R (Step S408).

Even in the frequency adjustment method according to the fourth embodiment, it is possible to suppress the occurrence of spurious due to the frequency adjustment as well as the resonance frequency F _R of the piezoelectric thin film resonator 1 as in the frequency adjustment method according to the first embodiment. Can be adjusted in the atmosphere.

It is sectional drawing which shows typically the wafer W used as the application object of the adjustment method of the resonant frequency of the piezoelectric thin film resonator which concerns on 1st Embodiment of this invention. 2 is a cross-sectional view showing a state where a wafer W is separated into individual piezoelectric thin film resonators 1. FIG. It is a flowchart explaining the adjustment method of the resonant frequency of the piezoelectric thin film resonator which concerns on 1st Embodiment of this invention. It is sectional drawing which shows typically the wafer W in the middle of frequency adjustment. It is sectional drawing which shows typically the wafer W in the middle of frequency adjustment. It is sectional drawing which shows typically the wafer W in the middle of frequency adjustment. It is a flowchart explaining the adjustment method of the resonant frequency of the piezoelectric thin film resonator which concerns on 2nd Embodiment of this invention. It is a flowchart explaining the adjustment method of the resonant frequency of the piezoelectric thin film resonator which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows typically the wafer W in the middle of frequency adjustment. It is a flowchart explaining the adjustment method of the resonant frequency of the piezoelectric thin film resonator which concerns on 4th Embodiment of this invention. It is sectional drawing which shows typically the wafer W in the middle of frequency adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric thin film resonator 11 Support substrate 12 Adhesive layer 13 Cavity formation film 15 Lower surface electrode 16 Piezoelectric thin film 17 Upper surface electrode 19 Resist film E1 Opposite area W Wafer

Claims (7)

Forming a mass addition film for adding mass on the piezoelectric thin film resonator, and lowering a resonance frequency of the piezoelectric thin film resonator from a target frequency;
Resonance of the piezoelectric thin film resonator by ablating the mass-added film by irradiating electromagnetic waves and uniformly thinning the entire mass-added film without affecting the planar pattern of the mass-added film An irradiation process to raise the frequency to the target frequency;
With
In the piezoelectric thin film resonator, the electrode pair is opposed across the piezoelectric thin film,
The forming step includes
A method for adjusting a resonance frequency of a piezoelectric thin film resonator, wherein the mass addition film is formed over the entire facing region where the electrode pair faces with the piezoelectric thin film interposed therebetween, and the mass addition film is formed only in the facing region. . The forming step includes
A film forming step of forming a photosensitive resin film;
A patterning step of patterning the photosensitive resin by photolithography to obtain the mass addition film;
A method for adjusting the resonance frequency of the piezoelectric thin film resonator according to claim 1. The irradiation step irradiates the electromagnetic wave while measuring the resonance frequency of the piezoelectric thin film resonator, and stops the irradiation of the electromagnetic wave in synchronization with the resonance frequency of the piezoelectric thin film resonator rising to the target frequency.
A method for adjusting a resonance frequency of the piezoelectric thin film resonator according to claim 1. Prior to the irradiation step, a determination step of determining the irradiation condition of the electromagnetic wave according to the difference between the resonance frequency of the piezoelectric thin film resonator and the target frequency,
The method for adjusting the resonance frequency of the piezoelectric thin film resonator according to claim 1, further comprising: In the forming step, the mass addition film is formed on each piezoelectric thin film resonator included in the piezoelectric thin film resonator assembly,
In the irradiation step, the assembly is irradiated with electromagnetic waves having a distribution of irradiation conditions according to a distribution of resonance frequencies of the piezoelectric thin film resonators in the assembly.
A method for adjusting a resonance frequency of the piezoelectric thin film resonator according to claim 1. In the forming step, the mass addition film is formed on each piezoelectric thin film resonator included in the piezoelectric thin film resonator assembly,
In the irradiation step, the aggregate is irradiated with an electromagnetic wave having a uniform irradiation condition according to a deviation between a representative value of a resonance frequency of the piezoelectric thin film resonator in the aggregate and a target frequency.
A method for adjusting a resonance frequency of the piezoelectric thin film resonator according to claim 1. A piezoelectric thin film;
A pair of electrodes facing each other across the piezoelectric thin film;
A mass-added film formed on a laminated structure including the piezoelectric thin film and the electrode pair, the mass of which is adjusted by ablation processing according to a deviation between a resonance frequency of the laminated structure and a target frequency;
With
The mass-added film is formed on the entire facing region where the electrode pair faces each other with the piezoelectric thin film interposed therebetween, and is formed only on the facing region , so that the entire surface is uniform without affecting the planar pattern. thinned piezoelectric thin film resonator in.

Images